System on a chip is an integrated circuit that includes a processor, a bus, and other elements on a single monolithic substrate. A system on a chip may include a configurable logic unit. The configurable logic unit includes a processor, interface, and a programmable logic on the same substrate.
Generally, systems on a chip are tested using external test gear. However, this is inconvenient, as it requires expensive test equipment, and eliminates the possibility of testing in the field.
One prior art method of solving the problem of testing for a non-configurable system on a chip is using a built-in-self-test (BIST) mechanism. However, a configurable system on a chip, one that includes configurable logic, is not compatible with the self-testing systems that currently exist. Therefore, alterations to the system-on-chip are needed, to simplify self-testing and to make self-testing more comprehensive.